hãy chứng tỏ các phân số sau bằng nhau
14/34 và 154/374
17/18;1717/1818 và 171717/181818
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Bài 1:
a) Rút gọn:
\(\dfrac{12}{30}=\dfrac{12:6}{30:6}=\dfrac{2}{5}\)
Mẫu số chung 2 phân số: 20
\(\dfrac{1}{4}=\dfrac{1\cdot5}{4\cdot5}=\dfrac{5}{20}\)
\(\dfrac{2}{5}=\dfrac{2\cdot4}{5\cdot4}=\dfrac{8}{20}\)
\(\dfrac{25}{75}=\dfrac{25:25}{75:25}=\dfrac{1}{3}\)
b) Mẫu số chung 2 phân số: 21
\(\dfrac{1}{3}=\dfrac{1\cdot7}{3\cdot7}=\dfrac{7}{21}\)
\(\dfrac{1}{7}=\dfrac{1\cdot3}{7\cdot3}=\dfrac{3}{21}\)
Bài 2:
a)
\(\dfrac{14}{34}=\dfrac{14:2}{34:2}=\dfrac{7}{17}\)
\(\dfrac{154}{374}=\dfrac{154:22}{374:22}=\dfrac{7}{17}\)
Vì \(7=7\) nên\(\dfrac{7}{17}=\dfrac{7}{17}\)
Vậy \(\dfrac{14}{34}=\dfrac{154}{374}\)
b)
\(\dfrac{17}{18}=\dfrac{17:1}{18:1}=\dfrac{17}{18}\)
\(\dfrac{1717}{1818}=\dfrac{1717:101}{1818:101}=\dfrac{17}{18}\)
\(\dfrac{171717}{181818}=\dfrac{171717:10101}{181818:10101}=\dfrac{17}{18}\)
Vậy \(\dfrac{17}{18}=\dfrac{1717}{1818}=\dfrac{171717}{181818}\)
1717/1919 = 17.101/19.101
171717/191919 = 17.10101/19.10101
→ 17/19 = 1717/1919 = 171717/191919
Ta thay : 17/19 = 17x1/19x1
1717/1919 = 17x101/19x101
171717/191919 = 17x10101/19x10101
Nen 17/19 = 1717/1919 = 171717/191919.
Nho k minh nha!
\(\dfrac{143}{363}\) = \(\dfrac{143:11}{363:11}\) = \(\dfrac{13}{33}\) (đpcm)
\(\dfrac{1212}{2727}\) = \(\dfrac{1212:101}{2727:101}\) = \(\dfrac{12}{27}\) (đpcm)
\(\dfrac{13}{33}\) và \(\dfrac{143}{363}\)
\(\dfrac{13}{33}=\dfrac{13\times11}{33\times11}=\dfrac{143}{363}\)
\(\dfrac{143}{363}=\dfrac{143\times1}{363\times1}=\dfrac{143}{363}\)
\(\dfrac{1212}{2727}\) và \(\dfrac{12}{27}\)
\(\dfrac{12}{27}=\dfrac{12\times101}{27\times101}=\dfrac{1212}{2727}\)
\(\dfrac{1212}{2727}=\dfrac{1212\times1}{2727\times1}=\dfrac{1212}{2727}\)
Anh giải ở câu hỏi trước rồi nhé em!
\(\dfrac{14}{34}\) = \(\dfrac{14:2}{34:2}\) = \(\dfrac{7}{17}\)
\(\dfrac{154}{374}\) = \(\dfrac{154:22}{374:22}\) = \(\dfrac{7}{17}\)
Vậy \(\dfrac{14}{34}\) = \(\dfrac{154}{374}\)
\(\dfrac{1717}{1818}\) = \(\dfrac{1717:101}{1818:101}\) = \(\dfrac{17}{18}\)
\(\dfrac{171717}{181818}\) =\(\dfrac{171717:10101}{181818:10101}\) = \(\dfrac{17}{18}\)
Vậy \(\dfrac{17}{18}\) = \(\dfrac{1717}{1818}\) = \(\dfrac{171717}{181818}\)